1. Technical Field
The following description relates to an organic light emitting display device, and more particularly, to a touch screen integrated organic light emitting display device which has a thin profile and is implemented in a flexible type, and a method for fabricating the same.
2. Discussion of the Related Art
As examples of flat display devices, there are liquid crystal display devices (LCDs), organic light emitting display devices, plasma display panel devices (PDPs), quantum dot display devices, field emission display devices (FEDs), electrophoretic display devices (EPDs), etc. Each of these flat display devices essentially includes a flat display panel for displaying an image in which a pair of transparent insulating substrates facing each other is bonded to each other, with an intrinsic light emitting layer, a polarizing layer or other optical material layers being interposed there between.
In an organic light emitting display device among these flat display devices, as requirement for a flat display element having a small space occupation is increased according to a recent large-sized trend of display devices, an organic electric field light emitting device referred to as an organic light emitting diode (OLED) has been rapidly developed as one of the flat display devices and various sample products have come into the market.
The organic light emitting display device does not require a separate light source and includes organic light emitting diodes spontaneously emitting light in the unit of pixels. The organic light emitting display device is considered the next generation display device since a light source and a structure to assemble the light source to a display panel are not required.
In the organic light emitting display device, electrons and holes are injected into a light emitting layer from an electron injection electrode (a cathode) and a hole injection electrode (an anode), respectively when a voltage is applied across the electron injection electrode (a cathode) and the hole injection electrode (an anode), and excitons, which are formed when the injected electrons and holes are combined, emit light when they transition from an excited state to a ground state.
Further, the requirement that a touch panel, which can recognize a touch point contacted by a human hand or other input unit and transmit the information concerning the contact, be added to the above display device has increased. Recently, such a touch panel attached to the external surface of the display device is employed.
Touch panels are divided into a resistive type, a capacitive type, and an infrared sensing type. Presently, the capacitive type touch panel is better than other types of touch panels in terms of fabrication and sensitivity.
Hereinafter, a conventional organic light emitting display device to which a touch screen is attached will be described with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view illustrating a conventional organic light emitting display device to which a touch screen is attached.
As shown in FIG. 1, the conventional organic light emitting display device includes an organic light emitting display panel 10, a touch screen 20 and a cover glass 30 which are sequentially stacked, and first and second adhesive layers 15 and 25 are provided between the light emitting display panel 10 and the touch screen 20 and between the touch screen 20 and the cover glass 30, respectively.
Although not illustrated in FIG. 1, the organic light emitting display panel 10 includes a substrate, a thin film transistor array arranged on the substrate in a form of matrix, and organic light emitting diodes connected to respective thin film transistors of the thin film transistor array. A passivation film and a polarizing layer are further provided (not shown) to cover the thin film transistor array. In this case, the first adhesive layer 15 is disposed on the upper surface of the polarizing layer.
The above-described conventional organic light emitting display device to which the touch screen is attached has the following problems.
First, if the organic light emitting display panel 10 and the touch screen 20 are separately formed and then the touch screen 20 is attached to the organic light emitting display panel 10, a cover glass 30 to protect the touch screen 20 is required, and the total thickness of the touch screen 20 including the stacked cover glass 30 and the organic light emitting display panel 10 is increased and thus it is difficult to implement the organic light emitting display device having a thin profile in a flexible type.
Second, since the organic light emitting display panel 10 and the touch screen 20 are separately formed, a process for forming the organic light emitting display panel 10 and a process for forming the touch screen 20 are required and thereby yield is low and cost is high.
Third, a polarizing plate optically blocking external light (not shown) is provided on the upper surface of the organic light emitting display panel 10, and thereby, when the touch screen 20 is formed thereon, an electrode pattern in the touch screen may be visible.